A gaunt, hollow-eyed defendant, staring straight ahead from under a woolen cap. A soldier ordered to erase videos of a crime. A military trial system that favors just the facts, and a prosecutor not keen to muddy the case with speculation.

US Maj. Nidal Malik Hasan's pre-trial hearing at Fort Hood for killing 13 fellow soldiers and maiming many more a year ago has so far featured startling testimony about how Major Hasan opened fire at a base deployment center, hunting people amid gun smoke with a red laser sight while shouting, "Allahu Akbar," or "Allah is greater."

Yet the motive for the shootings remains as unreachable as Hasan, who is partially paralyzed from getting shot after the rampage, and who has given few clues as to his state of mind. What's more, testimony from one soldier that he was ordered to erase two cell phone videos of the massacre scene – and attempts by Hasan's defense to paint the shooting spree as a rash, spontaneous, act – darken the prospect that Americans will learn what caused what some believe was the first international terror attack on US soil since 9/11.

"If people want to know about some overarching conspiracy to attack the United States, I'm not sure if that will come out [in a trial]," says Richard Rosen, a former staff judge advocate at Fort Hood and currently a law professor at Texas Tech. "We're more likely to hear about his state of mind when he committed the murders."

Congressional reports on the Fort Hood shooting have highlighted the veteran soldier's contact with Anwar Al-Awlaki, a US-born cleric known to foment violence against the US over the Internet. Personal problems, inappropriate statements at work, and a looming deployment to Afghanistan all hint at a man driven to the brink, fueled by stories about war injustices he'd heard from US soldiers returning from combat in Iraq and Afghanistan.

In September, Department of Homeland Security Secretary Janet Napolitano told a Senate panel that broader Al Qaeda strategy has diversified in terms of tactics and targets.

A key decision in the Fort Hood trial may be whether to introduce Hasan's email correspondence with Al-Awlaki, says Jarret Brachman, author of "Global Jihadism: Theory and Practice." "That would tell us volumes about the ideological direction he was receiving," he says. It's also possible that Hasan will eventually make a statement in court or introduce other evidence that could reveal his motivation.

As of now, experts say it's far from clear how much will eventually be revealed in the trial, especially about matters that could have national security implications. "If I were the government [prosecutor], I'm not sure why motive would matter except to prove that he's sane," says Mr. Rosen at Texas Tech. "I'm not sure I'd try to prove anything more than [pre-meditation] because I would not want to complicate the case."

But even as the trial may be short on Hasan's reasoning, two video accounts of the massacre that may have shown Hasan's demeanor during the shooting will not be seen and judged by the jury or the American public. One soldier testified Friday that a non-commissioned officer ordered him to erase two cellphone videos of the attack. While a "mystifying" and possibly illegal request, says Rosen, he hypothesized that it could have been intended to protect the privacy of Hasan's victims.

But some critics saw the order as evidence that the government, including the Army, is more concerned about protecting Muslims from backlash from angry Americans than revealing the truth behind how modern jihadi terrorism works. They point to the lack of words like "jihad" or "Muslim" in the Pentagon's official report on the Fort Hood massacre as proof that what they see as watered-down assumptions and hedged judgments about the Islamic threat to the US are hurting, not helping, national security.

"This rush to remove from our enemy's actions any suggestion of a possible Islamic religious motive reflects this administration's unwillingness to name our Islamist adversaries," writes a blogger at PipeLineNews, a consortium of conservative investigative journalists. "This is a critically serious threat to national security in that it places blinders on a defense establishment whose job it is to prevent further attacks."

At the hearing in a small, nondescript Fort Hood courtroom, Howitzers sound in the distance as witnesses, many still bearing scars from injuries sustained from Hasan's attack, describe the shooting in documentary detail. A presiding military judge will determine whether Hasan will face capital charges, where a 12-member military panel made up of high ranking officers could rule for the death penalty.

But while the trial may be be more about facts than motive, it will still likely give Americans a deeper understanding of what motivates a citizen to take up arms against representatives of his own country, says Mr. Brachman.

"It's cathartic for Americans to hear about this, to understand what happened and give us some sense of closure as a community," he says. "We tend to demonize these guys so readily, and I think we do ourselves a big disservice [by doing that]. When we paint them into devils and monsters, we miss the inherent human quality [of a terrorist]. That doesn't mean we have to sympathize, but to help us understand what got them to that point – to help us recognize [such plots] earlier."